At equilibrium the concentration of NO was found to be 0. Check to see if the amounts are expressed in moles per liter molarity since K c is being. In this example they are. Create an ICE chart that expresses the initial concentration, the change in concentration, and the equilibrium concentration for each species in the reaction. From the chart you can determine the changes in the concentrations of each species and the equilibrium concentrations.
From the example, we start with the folowing information. The change in concentration of the NO was 0. Note: the negative sign indicates a decreasing concentration, not a negative concentration. Solution As in previous textbox shaded, the definition of molarity is the primary equation used to calculate the quantity sought.
Check Your Learning Calculate the molarity of 6. Solution The volume and molarity of the solution are specified, so the amount mol of solute is easily computed as demonstrated in Example 2 :. Finally, this molar amount is used to derive the mass of NaCl:. When performing calculations stepwise, as in Example 4 , it is important to refrain from rounding any intermediate calculation results, which can lead to rounding errors in the final result.
In Example 4 , the molar amount of NaCl computed in the first step, 1. If we had not retained this guard digit, the final calculation for the mass of NaCl would have been In addition to retaining a guard digit for intermediate calculations, we can also avoid rounding errors by performing computations in a single step see Example 5. This eliminates intermediate steps so that only the final result is rounded. What volume of vinegar contains Solution First, use the molar mass to calculate moles of acetic acid from the given mass:.
Then, use the molarity of the solution to calculate the volume of solution containing this molar amount of solute:. Check Your Learning What volume of a 1. Dilution is the process whereby the concentration of a solution is lessened by the addition of solvent. For example, we might say that a glass of iced tea becomes increasingly diluted as the ice melts. The water from the melting ice increases the volume of the solvent water and the overall volume of the solution iced tea , thereby reducing the relative concentrations of the solutes that give the beverage its taste Figure 3.
Dilution is also a common means of preparing solutions of a desired concentration. By adding solvent to a measured portion of a more concentrated stock solution , we can achieve a particular concentration. For example, commercial pesticides are typically sold as solutions in which the active ingredients are far more concentrated than is appropriate for their application.
Before they can be used on crops, the pesticides must be diluted. This is also a very common practice for the preparation of a number of common laboratory reagents Figure 4.
A simple mathematical relationship can be used to relate the volumes and concentrations of a solution before and after the dilution process. Expressions like these may be written for a solution before and after it is diluted:. Thus, these two equations may be set equal to one another:. This relation is commonly referred to as the dilution equation. Although we derived this equation using molarity as the unit of concentration and liters as the unit of volume, other units of concentration and volume may be used, so long as the units properly cancel per the factor-label method.
Reflecting this versatility, the dilution equation is often written in the more general form:. Use the simulation to explore the relations between solute amount, solution volume, and concentration and to confirm the dilution equation. Determining the Concentration of a Diluted Solution If 0.
Solution We are given the volume and concentration of a stock solution, V 1 and C 1 , and the volume of the resultant diluted solution, V 2. We need to find the concentration of the diluted solution, C 2. We thus rearrange the dilution equation in order to isolate C 2 :. Since the stock solution is being diluted by more than two-fold volume is increased from 0. We will compare this ballpark estimate to the calculated result to check for any gross errors in computation for example, such as an improper substitution of the given quantities.
Substituting the given values for the terms on the right side of this equation yields:. Check Your Learning What is the concentration of the solution that results from diluting Volume of a Diluted Solution What volume of 0. Solution We are given the volume and concentration of a stock solution, V 1 and C 1 , and the concentration of the resultant diluted solution, C 2. We need to find the volume of the diluted solution, V 2.
We thus rearrange the dilution equation in order to isolate V 2 :. Since the diluted concentration 0. Expressed as N for capacity analysis. Volume specific concentration Concentration indirectly expressed by the volume ratio of diluting the liquid reagent.
It is used in JIS and others. Weight ratio concentration Concentration indirectly expressed by weight ratio at which solid reagent is dissolved. Molarity Mol number of target substance solute in 1L of solution. Keyword search. Please contact us via the inquiry form.
0コメント